Surface charge retention and enhanced polarization effect on ferroelectric thin films

Abstract

The authors report surface charge retention and enhanced ferroelectric polarization effect on ferroelectric thin films by Kelvin probe force microscope (KFM). Since high electric field is induced at scanning probe microscope tip during domain switching and the sign of surface charge induced by this high electric field is always opposite to the sign of induced ferroelectric polarization charge, the surface potential of the KFM signal exhibits the relative potential difference between the potential of the ferroelectric polarization charge and the potential of the surface charge. After the discharge process of surface charge, the enhanced contribution from the ferroelectric polarization charge was observed. Similarly, the reduction of surface charge was observed as time passed and the surface potential indicating the ferroelectric polarization charge was enhanced due to this retention property of surface charge.